1. (Field of the Invention)
The present invention relates to a novel chromene compound and to a photochromic polymerizable composition containing the chromene compound. The invention is further related to a photochromic material containing the chromene compound and, particularly, to a photochromic optical material.
2. (Background of the Invention)
Photochromism is a phenomenon that is drawing attention in the past several years, and stands for a reversible action of a compound which quickly changes its color when it is irradiated with light containing ultraviolet rays such as sun light or light from a mercury lamp and resumes its initial color when it is no longer irradiated with light but is placed in a dark place. The compound having this property is called photochromic compound, and various compounds have heretofore been synthesized without, however, any particular common nature in their structures.
International Patent Publication WO96/14596 discloses a chromene compound represented by the following formula (A), 
However, this chromene compound has a low color-developing sensitivity and a low fading rate. When used for extended periods of time as a photochromic material, further, this chromene compound is colored to a large extent (also called coloring after aged) in a state of not being irradiated with light and exhibits a decreased color density when irradiated with light.
Further, International Patent Publication WO97/48762 discloses a chromene compound represented by the following formula (B), 
However, this chromene compound has a problem of a low color fading rate.
Further, German Patent Application Publication DE 19902771 A1 discloses in its Examples 4, 7 and 5 the chromene compounds represented by the following formulas (C), (D) and (E) 
However, these chromene compounds have such problems that their color-developing sensitivities are low and, besides, their fading rates are not of satisfactory levels.
The object of the present invention is to provide a chromene compound featuring further improved photochromic properties compared to those of the above-mentioned compounds, exhibiting a high color-developing sensitivity, a high fading rate, being little colored after aged, and permitting the photochromic properties to be little deteriorated, i.e., permitting the color density to drop little, and exhibiting excellent durability of photochromic property.
The present invention was proposed in order to accomplish the above-mentioned object, and was completed based on a knowledge that the novel chromene compound which was obtained by the present inventors exhibits a high color-developing sensitivity, a large fading rate, a small coloring after aged, and excellent durability of photochromic property.
That is, according to the present invention, the chromene compound is represented by the following general formula (1), 
wherein,
R1 is an alkyl group, a hydroxy group, an alkoxy group, an aralkoxy group, an amino group, a substituted amino group, a cyano group, a nitro group, a substituted or unsubstituted aryl group, a halogen atom, a trifluoromethyl group, an aralkyl group, a monovalent heterocyclic group bonded to the indene ring through the carbon atom, a monovalent substituted or unsubstituted heterocyclic group having a nitrogen atom as a hetero atom and bonded to the indene ring through the nitrogen atom, or a monovalent condensed heterocyclic group in which said heterocyclic group is condensed with an aromatic hydrocarbon ring or an aromatic heterocyclic ring, p is an integer of from 0 to 3;
a divalent group represented by the following formula (2), 
xe2x80x83is an aromatic hydrocarbon group or an unsaturated heterocyclic ring;
R2 is an alkyl group, a hydroxy group, an alkoxy group, an aralkoxy group, an amino group, a substituted amino group, a cyano group, a nitro group, a substituted or unsubstituted aryl group, a halogen atom, a trifluoromethyl group, an aralkyl group, a monovalent heterocyclic group bonded to the ring of the group represented by the above formula (2) through the carbon atom, a monovalent substituted or unsubstituted heterocyclic group having a nitrogen atom as a hetero atom and is bonded to the ring of the group represented by the above formula (2) through the nitrogen atom, or a monovalent condensed heterocyclic group in which said heterocyclic group is condensed with an aromatic hydrocarbon ring or an aromatic heterocyclic ring, q is an integer of from 0 to 3;
R3 and R4 are, independently from each other, group represented by the following formula (3), 
wherein R5 is a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group, R6 is a hydrogen atom, an alkyl group or a halogen atom, and n is an integer of from 1 to 3;
group represented by the following formula (4), 
xe2x80x83wherein R7 is a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group, and m is an integer of from 1 to 3;
substituted or unsubstituted aryl groups, or substituted or unsubstituted heteroaryl groups, or;
R3 and R4 are group which, in combination, constitute an aliphatic hydrocarbon ring or an aromatic hydrocarbon ring; and
X is represented by any one of the following formula, 
xe2x80x83wherein Z is an oxygen atom or a sulfur atom, R8 is an alkylene group with 1 to 6 carbon atoms, and a, b, c and d are integers of from 1 to 4 independently from each other.
As represented by the above-mentioned general formula (1), the chromene compound of the present invention has a basic structure in which:
{circle around (1)} a condensed ring formed by a particular divalent group xe2x80x94Xxe2x80x94 bonded to the carbon atoms at the fourth and fifth positions of the fluorene ring, is spiro-bonded to the first position of the indene ring;
{circle around (2)} a condensed ring is formed by a divalent group represented by the above general formula (2) bonded to the carbon atoms at the fifth and sixth positions of the chromene ring; and
{circle around (3)} particular substituents are bonded to the carbon atom at the second position of the chromene ring.
As will become obvious from the comparison of Examples and Comparative Examples appearing later, possession of the above-mentioned three features in combination makes it possible to obtain excellent effects mentioned above.
It is desired that the chromene compound of the present invention is the one represented by the following general formula (6), 
wherein R15 and R16 are, independently from each other, alkyl group with 1 to 4 carbon atoms, alkoxy group with 1 to 5 carbon atoms, aralkoxy group with 6 to 10 carbon atoms; mono-substituted or di-substituted amino group having, as a substituent, an aralkyl group with 1 to 4 carbon atoms or an aryl group with 6 to 10 carbon atoms, cyano group, aryl group with 6 to 10 carbon atoms, substituted aryl group with 6 to 10 carbon atoms (without including carbon atoms of a substituent) substituted with an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 5 carbon atoms, halogen atom, or substituted or unsubstituted heterocyclic groups having a nitrogen atom as a hetero atom, being bonded to the indene ring or the naphthalene ring through the nitrogen atoms, and being selected from morpholino group, piperidino group, pyrrolidinyl group, 1-piperazinyl group, 4-methyl-1-piperazinyl group or indolinyl group, or condensed heterocyclic group in which said heterocyclic group is condensed with an aromatic hydrocarbon ring or an aromatic heterocyclic ring;
at least either one of R13 and R14 is a substituted aryl group with 6 to 10 carbon atoms (without including carbon atoms of a substituent) having at least one substituent selected from a mono-substituted or di-substituted amino group having, as a substituent, an alkyl group with 1 to 4 carbon atoms or an aryl group with 6 to 10 carbon atoms, alkoxy group with 1 to 5 carbon atoms, morpholino group, piperidino group, pyrrolidinyl group, 1-piperazinyl group, 4-methyl-1-piperazinyl group and indolinyl group, or a heteroaryl group with 4 to 12 carbon atoms (without including carbon atoms of a substituent); and X is a divalent group represented by xe2x80x94CHxe2x95x90CHxe2x80x94.
Among the above-mentioned chromene compounds, it is desired that the chromene compound is the one represented by the above formula (6) in which R15 and R16 are, independently from each other, alkyl group with 1 to 4 carbon atoms; alkoxy group with 1 to 5 carbon atoms, halogen atom, or morpholino group and, most desirably, methyl group or methoxyl group; at least either one of R13 and R14 is a substituted aryl group with 6 to 10 carbon atoms (without including carbon atoms of a substituent) having at least one substituent selected from a mono-substituted or di-substituted amino group having, as a substituent, an alkyl group with 1 to 4 carbon atoms or an aryl group with 6 to 10 carbon atoms, alkoxy group with 1 to 5 carbon atoms, morpholino group, piperidino group, pyrrolidinyl group, 1-piperazinyl group, 4-methyl-1-piperazinyl group and indolinyl group; and when either one of R13 and R14 is not the above group, the other one is an aryl group with 6 to 10 carbon atoms, or a heteroaryl group with 4 to 12 carbon atoms, and most desirably, either one of R13 and R14 is a phenyl group having a piperidino group, a morpholino group or a methoxyl group as a substituent, and the other one is a phenyl group or a methoxyphenyl group.
The invention is further concerned with a photochromic material comprising a chromene compound represented by the above-mentioned general formula (1), and with a photochromic optical material containing the chromene compound.
According to the present invention, there is further provided a photochromic polymerizable composition containing:
the above-mentioned chromene compound;
a polymerizable monomer (particularly, a (meth)acrylic acid ester compound); and
if necessary, a polymerization initiator.